This is excellent. I'm a fan of well done bird pics, and this is extremely well done. It's so crisp it's hard to imagine it was only an 800 shutter. Beautiful eye detail too.
Hey! Submit this to Birder's World. I don't know how you did this with 300mm. Best "Marsh Hawk" image I've ever seen. Also, this is something you should submit to David Sibley's iPhone app, or Audobon's. Seriously. Great job!
Nice job of desaturating the BG. This is a very nice capture of a Northern Harrier. They are commonly found near Marsh areas. The white patch on the rump is their tell tale marking. This would be a female. The male is smaller and mostly gray. I've been trying to get a shot of one of these for a while. You did good!!